oil blow by into air filter

There was a big discussion about this 2-3 weeks ago so you may want to scroll back a bit or do a search.

Basically, I think... and please notice I am voicing my personal opinion... that when the cylinder walls wear, you have more blow-by past the rings when the piston is on the compression stroke. When the piston moves down in the power stroke, the gases that passed by the rings are now pushed into the crankcase. This gas must now be vented somewhere. The PCV (Positive Crankcase Ventilation) system takes a large part of the gas away. However, as the cylinder walls wear and the pressure inside the crankcase increases, the PCV can't handle all of it. And so the gas vents out the only other hole in the valve cover and that is the one that is connected directly to the air filter housing.

You can buy a oil blow-by filter or a breater filter that will help separate the oil from the vapor and reduce the oil in your housing and keep it from gunking up the air filter. You can do a compresson check to confirm if this is the cause. Hope this makes sense. Good luck.

One of the problems is that the 258 is so reliable and built so well, that it continues to run well into the time that it shouldn't. /wwwthreads_images/icons/smile.gif. I got about 194,000 out of my first one. I had blow-by so bad that I rigged up a system to catch all the oil, and still vent the valve cover. I went to NAPA, and bought a 90 degree elbow that fit in the rear valve cover grommet, and some heater hose. I ran the heater hose over to behind the windsheild washer bottle (always going downhill), and went to a "T", installed sideways. The downspout of the "T" I put into a quart plastic oil jug, with hose clamps, to catch the oil, and the top of the "T" I put to a breather. It really was amazing how much oil would come out of that motor. /wwwthreads_images/icons/crazy.gif Being on the highway at high rpms was the worst. I have since put in a rebuilt 258. /wwwthreads_images/icons/smile.gif

Also, in your PCV line, between the valve and the intake/carb, there are some restrictors - small plastic things with small holes, I guess to reduce the flow of air getting to the pcv. These will clog also, and you'll get no suction to the pcv valve, so watch those.

Good luck
Pete

88YJ,4"susp,33"BFGMT,9kwinch,homemade swingout,258,999,4.10,weber32/36,GMHEI,one moonguy/wwwthreads_images/icons/smile.gif

Look here:
http://store.summitracing.com/produ...L3HQTH&p=A6ED2583-3612-11D3-949D-080009FC5B5F

You can fab something like this yourself .....I did (a while back)......the idea is to give it some place to lower the velocity (like a shop vac).....if you hang the thing high enough you should be able to just use one inlet on the bottom and it will drain back on its own assuming that you don't have EXCESSIVE (read engine is really null and void) blow by.

GeeAea

Figures don't lie ....... but liars sure do figure.